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Interstellar Travel Now

Interstellar Travel Now. Agenda. RFP Proposal Sub-topics. Request for Proposal. Under current or near term technology what can be done to send a robotic probe to a nearby star? Define reasonable cost and flight time What is the minimum probe and engine mass?

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Interstellar Travel Now

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  1. Interstellar Travel Now HYPERION ERAU

  2. Agenda • RFP • Proposal • Sub-topics HYPERION ERAU

  3. Request for Proposal • Under current or near term technology what can be done to send a robotic probe to a nearby star? • Define reasonable cost and flight time • What is the minimum probe and engine mass? • How long from launch until stellar arrival? • How much will it cost? • Why is this preferred to telescopes? HYPERION ERAU

  4. Issues • If this is done via • propulsive methods • the following are • issues • Fuel Energy Density • Specific Impulse • Thrust/Acceleration HYPERION ERAU

  5. Assumptions • Consider a probe launched from a C3=0 orbit on a fly-by mission of α-Centari • Consider vehicle mass fractions of 20000, 2000, and 200 • All probes with ΔV’s of less than 0.05c require 6 months of acceleration • All probes with a ΔV of more than 0.05c require 18 months of acceleration • Trip time is a function of Isp HYPERION ERAU

  6. Flight Time (years) vs. Isp • Rapid interstellar flight requires millions of seconds of Isp • This can only be accomplished via antimatter propulsion, • laser accelerated proton propulsion or solar sails • -All of the above systems are out of current technical grasp HYPERION ERAU

  7. Flight Time (years) vs. Isp HYPERION ERAU

  8. Flight Time (years) vs. Isp HYPERION ERAU

  9. Case Studies HYPERION ERAU

  10. Investigated Propulsion Systems • Plasma Core Nuclear Thermal Rocket (NTR) • Nuclear Electric Propulsion - 10 MWe core or larger - Consider Ion, Hall Effect, MPD thrusters • Nuclear Fusion - Different fuel cycles (D-T, D-D, D-He3+, pB, spin polarized fuels) - Magnetic Confinement Fusion (MCF) - Inertial Confinement Fusion (ICF) - Magnetically Insulated ICF (MICF) - Antiproton Initiated Fusion (AIF) • Antimatter Propulsion (beamed core) - proton-antiproton - electron-positron - hydrogen-antihydrogen HYPERION ERAU

  11. Plasma Core NTR - Requires 106 K for 20,000 s + Isp - Contamination a problem • Plasma containment a • problem • Probably not feasible HYPERION ERAU

  12. NEP • Fission Reactor produces • electrical power • -Electrical power runs • electrostatic or electromagnetic • thruster • -Can run Ion, MPD, Arc Jets, • and Hall Effect thrusters • -Very realistic Problems include power processing, grid erosion, high temperature Materials, but it is feasible to build engines at 30,000-100,000 second Isp’s HYPERION ERAU

  13. NEP Thrusters MPD Ion ~ 3000 – 100,000 s of Isp Isp can depend on propellant Isp can depend on efficiency Isp depends largely on input power HYPERION ERAU

  14. 30 ks NEP • What input power is required to obtain 30 ks of specific impulse? • How much waste heat does this produce? • How do we dissipate the waste heat? HYPERION ERAU

  15. 100 ks NEP • What input power is required to obtain 100 ks of specific impulse? • How much waste heat does this produce? • How do we dissipate the waste heat? HYPERION ERAU

  16. Fusion • Fusion of light elements provides propulsive source of energy • Releases ~ 1014 J/kg HYPERION ERAU

  17. Fusion Fuel Cycles D-T: Low ignition temp. High neutron yield 1st generation fuel D-D: Large energy yield Thermal radiation D-He3+: Large energy yield Thermal radiation Spin Polarized Fuels HYPERION ERAU

  18. Magnetic Confinement Fusion • Tokomak • Torodial fields • Polodial field • Spheromak • Similar to Tokomak • Slightly higher Q • Slightly higher α - Plasma is ejected as rocket exhaust -Under Lawson’s criteria all MCF techniques require low ion densities and long burn times -All MCF techniques are very heavy and have no applications as an electrical power producing device HYPERION ERAU

  19. Magnetic Confinement Fusion Gas Dynamic Mirror • Similar to a z-pinch • Ions with precise θ escape • Escaping ions produce thrust • Potentially 50-100,00 s of Isp • Very heavy • Potentially near term if it burns D-T mixture HYPERION ERAU

  20. Inertial Confinement Fusion • Particle beams or lasers • compress fusile targets • -Magnets must contain plasma • for short time frames • -Drivers are very heavy • must be ~1.6 MJ • -Higher Q’s than MCF • -Higher α than MCF • -High ion densities (neutron star), short confinement time • - If weight can be negated this has serious potential in propulsion!! HYPERION ERAU

  21. Magnetically Insulated ICF • Tungsten or gold surrounds • target pellet • Low thermal impulse • on tungsten shield • -Produces transient magnetic • field • -Reduces need for magnets • -Ablated Tungsten reduces • Isp • Drastically reduces mass of drivers • and electromagnets!! HYPERION ERAU

  22. Antiproton Initiated ICF • Muon Catalyzed Fusion • Antiproton annihilation creates • μ-mesons (muons) • -muons displace electrons around • nucleus • -must occur at low energies • (1200 – 1600 K) • -no or little need for drivers • -combined with MICF makes • a lightweight engine • Requires nano-grams of antiprotons HYPERION ERAU

  23. Antiproton Initiated ICF Antimatter Initiated Micro-Fusion/Fission • Antiprotons induce U238 fission • Released neutrons help compress fusion fuel • Larger α than muon catalyzed fusion • Isp ~ 50,000 s – 1,000,000 s HYPERION ERAU

  24. Antimatter Propulsion • Highest performance under the laws of impulse and momentum • Requires kilograms of antimatter which is not yet available • Offers Isp near the theoretical limit (30.6 x 106 seconds • The only hope for rapid robotic or manned • interstellar propulsion HYPERION ERAU

  25. Antiproton • ~35% of annihilation energy • is lost to massive particles • Requires 2 km long nozzle • Large radiation levels due • to pions and muons HYPERION ERAU

  26. Positron • Uses momentum from 0.511 MeV • photons • Requires reflection of high energy • photons • Positrons easier to produce than • antiprotons • - Very high burnout velocities HYPERION ERAU

  27. Investigation Questions • Does the technology exist now? • If not can it be developed in 15 years assuming unlimited funds? • Or can the system not be developed with current physical understanding? HYPERION ERAU

  28. Investigated Parameters • What is the system mass? • What is the system thrust? • What is the system Isp? • What is the fastest the system can reach α-centari? • What is the systems TRL now? • What is the cost of developing this system? • What is the cost of launching this system? HYPERION ERAU

  29. Investigated Parameters • What is the cost of transferring the craft from LEO to C3=0? (assume the use on an NTR) • What the minimum engine mass? HYPERION ERAU

  30. Probe Design • What are the data transfer signal requirements for transmitting over 4.56 ly? - beam vs. isotropic signal - S/N ratio - Transmission Power - Pointing accuracy • What are the thermal control, attitude control, and navigation requirements - The stars will not be in the same place to use star trackers • What are the total power requirements for the probe? - Do we need an onboard fission reactor or can we shut down the craft during flight and use solar arrays when it arrives near its target, or even use batteries that only last 15 minutes? HYPERION ERAU

  31. Probe Question • How does the info. from the previous slide drive the probe mass? • What is the craft dry mass when the probe mass is combined with the engine mass? • At MR’s of 20,000, 2000, and 200 what is the total craft mass for each case, when propellant is added to the dry mass? HYPERION ERAU

  32. Questions • ??? HYPERION ERAU

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